Many modern syntactic theories assume that the syntactic structures encode hierarchical information but not linear order. Basically, the syntax encodes "above" and "below," but not "earlier" and "later." Much of my syntactic research is focused on linearization, the process of assigning order to hierarchical syntactic structures. Specific issues I have worked include:
the linearization of "right node raising" constructions (e.g., Darius found __ and Jasmine took the book);
how to resolve mismatches between syntactic structure and linear order; and
how to represent linear order mathematically.